Three-dimensional memory device with source structure and methods for forming the same

ABSTRACT

Embodiments of structure and methods for forming a three-dimensional (3D) memory device are provided. In an example, a 3D memory device includes a memory stack over a substrate, a plurality of channel structures, a source structure, and a support structure. The memory stack includes interleaved a plurality of conductor layers and a plurality of insulating layers. The plurality of channel structures extend vertically in the memory stack. The source structure includes a plurality of source portions and extending in the memory stack. The support structure is between adjacent ones of the source portions and has a plurality of interleaved conductor portions and insulating portions. A top one of the conductor portions is in contact with a top one of the conductor layers. Adjacent ones of the source portions are conductively connected to one another.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is continuation of International Application No.PCT/CN2020/077407, filed on Mar. 2, 2020, entitled “THREE-DIMENSIONALMEMORY DEVICE WITH SOURCE STRUCTURE AND METHODS FOR FORMING THE SAME,”which is hereby incorporated by reference in its entirety.

BACKGROUND

Embodiments of the present disclosure relate to three-dimensional (3D)memory devices having source structures of reduced resistance andimproved support, and methods for forming the 3D memory devices.

Planar memory cells are scaled to smaller sizes by improving processtechnology, circuit design, programming algorithm, and fabricationprocess. However, as feature sizes of the memory cells approach a lowerlimit, planar process and fabrication techniques become challenging andcostly. As a result, memory density for planar memory cells approachesan upper limit.

A 3D memory architecture can address the density limitation in planarmemory cells. 3D memory architecture includes a memory array andperipheral devices for controlling signals to and from the memory array.

SUMMARY

Embodiments of 3D memory devices and methods for forming the 3D memorydevices are provided.

In one example, a 3D memory device includes a memory stack over asubstrate, a plurality of channel structures, a source structure, and asupport structure. The memory stack includes interleaved a plurality ofconductor layers and a plurality of insulating layers. The plurality ofchannel structures extend vertically in the memory stack. The sourcestructure includes a plurality of source portions and extending in thememory stack. The support structure is between adjacent ones of thesource portions and has a plurality of interleaved conductor portionsand insulating portions. A top one of the conductor portions is incontact with a top one of the conductor layers. Adjacent ones of thesource portions are conductively connected to one another.

In another example, a 3D memory device includes a memory stack, aplurality of channel structures, a source structure, and a supportstructure. The memory stack has a plurality of memory blocks over asubstrate, each of the memory blocks having interleaved a plurality ofconductor layers and a plurality of insulating layers. The plurality ofchannel structures extend vertically in the memory blocks. The sourcestructure extend between adjacent memory blocks. The support structureis in contact with the source structure and having a plurality ofinterleaved conductor portions and insulating portions. Adjacent memoryblocks are in contact with each other through the support structure. Atop one of the conductor portions is in contact with a top one of theconductor layers in each of the adjacent memory blocks.

In a further example, a method for forming a 3D memory device includesthe following operations. First, a slit structure and a supportstructure are formed in a stack structure having interleaved a pluralityof sacrificial material layers and a plurality of insulating materiallayers, the initial support structure between adjacent slit openings ofthe slit structure. A source structure is formed to include a sourceportion in each of the slit openings. A pair of first portions of aconnection layer is formed in contact with and conductively connected tothe source portion. A second portion of the connection layer is formedin contact with and conductively to the pair of first portions of theconnection layer.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate embodiments of the present disclosureand, together with the description, further serve to explain theprinciples of the present disclosure and to enable a person skilled inthe pertinent art to make and use the present disclosure.

FIG. 1A illustrates a plan view of an exemplary 3D memory device havingsource structures of reduced resistance and improved support, accordingto some embodiments of the present disclosure.

FIG. 1B illustrates a cross-sectional view of the 3D memory deviceillustrated in FIG. 1A along the C-D direction, according to someembodiments of the present disclosure.

FIG. 1C illustrates a cross-sectional view of the 3D memory deviceillustrated in FIG. 1A along the A-B direction, according to someembodiments of the present disclosure.

FIG. 2A illustrates a plan view of an exemplary 3D memory device at onestage of a fabrication process, according to some embodiments of thepresent disclosure.

FIG. 2B illustrates a cross-sectional view of the 3D memory deviceillustrated in FIG. 2A along the C-D direction, according to someembodiments of the present disclosure.

FIG. 3A illustrates a plan view of the exemplary 3D memory device atanother stage of the fabrication process, according to some embodimentsof the present disclosure.

FIG. 3B illustrates a cross-sectional view of the 3D memory deviceillustrated in FIG. 3A along the C-D direction, according to someembodiments of the present disclosure.

FIG. 4A illustrates a plan view of the exemplary 3D memory device atanother stage of the fabrication process, according to some embodimentsof the present disclosure.

FIG. 4B illustrates a cross-sectional view of the 3D memory deviceillustrated in FIG. 4A along the C-D direction, according to someembodiments of the present disclosure.

FIG. 5A illustrates a plan view of the exemplary 3D memory device atanother stage of the fabrication process, according to some embodimentsof the present disclosure.

FIG. 5B illustrates a cross-sectional view of the 3D memory deviceillustrated in FIG. 5A along the C-D direction, according to someembodiments of the present disclosure.

FIG. 6A illustrates a plan view of the exemplary 3D memory device atanother stage of the fabrication process, according to some embodimentsof the present disclosure.

FIG. 6B illustrates a cross-sectional view of the 3D memory deviceillustrated in FIG. 6A along the C-D direction, according to someembodiments of the present disclosure.

FIG. 7A illustrates a plan view of the exemplary 3D memory device atanother stage of the fabrication process, according to some embodimentsof the present disclosure.

FIG. 7B illustrates a cross-sectional view of the 3D memory deviceillustrated in FIG. 6A along the C-D direction, according to someembodiments of the present disclosure.

FIG. 8A illustrates a plan view of an exemplary pattern set for formingvarious structures in a fabrication process for forming a 3D memorydevice, according to some embodiments of the present disclosure.

FIG. 8B illustrates an enlarged view of a portion of the pattern setshown in FIG. 8A, according to some embodiments of the presentdisclosure.

FIG. 9 illustrates a cross-sectional view of an existing 3D memorydevice with deformed gate line slits (GLSs).

FIGS. 10A and 10B illustrate a flowchart of an exemplary fabricationprocess for forming a 3D memory device having source structures ofreduced resistance and improved support, according to some embodimentsof the present disclosure.

Embodiments of the present disclosure will be described with referenceto the accompanying drawings.

DETAILED DESCRIPTION

Although specific configurations and arrangements are discussed, thisshould be understood that this is done for illustrative purposes only. Aperson skilled in the pertinent art will recognize that otherconfigurations and arrangements can be used without departing from thespirit and scope of the present disclosure. It will be apparent to aperson skilled in the pertinent art that the present disclosure can alsobe employed in a variety of other applications.

It is noted that references in the specification to “one embodiment,”“an embodiment,” “an example embodiment,” “some embodiments,” etc.,indicate that the embodiment described may include a particular feature,structure, or characteristic, but every embodiment may not necessarilyinclude the particular feature, structure, or characteristic. Moreover,such phrases do not necessarily refer to the same embodiment. Further,when a particular feature, structure or characteristic is described inconnection with an embodiment, it would be within the knowledge of aperson skilled in the pertinent art to affect such feature, structure orcharacteristic in connection with other embodiments whether or notexplicitly described.

In general, terminology may be understood at least in part from usage incontext. For example, the term “one or more” as used herein, dependingat least in part upon context, may be used to describe any feature,structure, or characteristic in a singular sense or may be used todescribe combinations of features, structures or characteristics in aplural sense. Similarly, terms, such as “a,” “an,” or “the,” again, maybe understood to convey a singular usage or to convey a plural usage,depending at least in part upon context. In addition, the term “basedon” may be understood as not necessarily intended to convey an exclusiveset of factors and may, instead, allow for existence of additionalfactors not necessarily expressly described, again, depending at leastin part on context.

As used herein, the term “nominal/nominally” refers to a desired, ortarget, value of a characteristic or parameter for a component or aprocess operation, set during the design phase of a product or aprocess, together with a range of values above and/or below the desiredvalue. The range of values can be due to slight variations inmanufacturing processes or tolerances. As used herein, the term “about”indicates the value of a given quantity that can vary based on aparticular technology node associated with the subject semiconductordevice. Based on the particular technology node, the term “about” canindicate a value of a given quantity that varies within, for example,10-30% of the value (e.g., ±10%, ±20%, or ±30% of the value).

As used herein, a staircase structure refers to a set of surfaces thatinclude at least two horizontal surfaces (e.g., along x-y plane) and atleast two (e.g., first and second) vertical surfaces (e.g., alongz-axis) such that each horizontal surface is adjoined to a firstvertical surface that extends upward from a first edge of the horizontalsurface, and is adjoined to a second vertical surface that extendsdownward from a second edge of the horizontal surface. A “step” or“staircase” refers to a vertical shift in the height of a set ofadjoined surfaces. In the present disclosure, the term “staircase” andthe term “step” refer to one level of a staircase structure and are usedinterchangeably. In the present disclosure, a horizontal direction canrefer to a direction (e.g., the x-axis or the y-axis) parallel with thetop surface of the substrate (e.g., the substrate that provides thefabrication platform for formation of structures over it), and avertical direction can refer to a direction (e.g., the z-axis)perpendicular to the top surface of the structure.

NAND flash memory devices, widely used in various electronic products,are non-volatile, light-weighted, of low power consumption and goodperformance. Currently, planar NAND flash memory devices have reachedits storage limit. To further increase the storage capacity and reducethe storage cost per bit, 3D NAND memory devices have been proposed. Anexisting 3D NAND memory device often includes a plurality of memoryblocks. Adjacent memory blocks are often separated by a GLS, in which anarray common source (ACS) is formed. In the fabrication method to formthe existing 3D NAND memory device, due to an increased number of levels(or conductor/insulator pairs), the etching process to form GLSs becomechallenging. For example, the GLSs can be more susceptible todeformation, e.g., fluctuation of feature size, causing memory blocksneighboring the GLSs to deform or even collapse. The performance of the3D NAND memory device can be affected.

FIG. 9 illustrates an existing 3D memory device 900 with deformed GLSsand a deformed memory block. As shown in FIG. 9, a memory stack 911 isformed over a substrate 902. A plurality of GLS, e.g., 906-1 and 906-2,extend through memory stack 911 to expose substrate 902. A plurality ofchannel structures 904 are arranged in a memory block between GLSs 906-1and 906-2. Due to deformation, a lateral dimension, e.g., diameter D, ofGLS (e.g., 906-1 or 906-2) varies along the vertical direction (e.g.,the z-direction), causing the memory block and channel structures 904,to move from their desired position/orientation. These deformations canlead to photolithography misalignment and electrical leakage insubsequent fabrication processes that form ACSs in the GLSs.

The present disclosure provides 3D memory devices (e.g., 3D NAND memorydevices) having source structures with reduced resistance and improvedsupport, and methods for forming the 3D memory devices. A 3D memorydevice employs one or more support structures that divide a slitstructure into a plurality of slit openings, in which source portionsare formed. The support structures are each in contact with adjacentmemory blocks, providing support to the entire structure of the 3Dmemory device during the formation of conductor layers/portions andsource contacts. The 3D memory device is then less susceptible todeformation or damages during the fabrication process.

In the 3D memory device, at least two adjacent source portions are incontact with and conductively connected to one another through aconnection layer, which includes a conductive material such as tungsten.One or more pairs of adjacent source portions in a source structure canbe in contact with and conductively connected together by the connectionlayer. Instead of applying a source voltage on each of the plurality ofsource portions using a respective contact plug, the source voltage isapplied on the source portions (e.g., the source portions that are incontact with connection layer) through the connection layer(s), reducingor eliminating the use of contact plugs. The resistance of the sourcestructure can be reduced. The contact area between the connection layerand a source portion can be sufficiently large to further reduce theresistance of the source structure. In some embodiments, the connectionlayer is in contact with and conductively connected to all the sourceportions in a source structure, further reducing the resistance of thesource structure. In addition, the fabrication of the support structuresand the source structures do not require additional fabrication steps orfabrication cost.

FIG. 1A illustrates a plan view of an exemplary 3D memory device 100,according to some embodiments. FIG. 1B illustrates a cross-sectionalview of the 3D memory device 100 shown in FIG. 1A along the C-Ddirection. FIG. 1C illustrates a cross-sectional view of the 3D memorydevice 100 shown in FIG. 1A along the A-B direction. As shown in FIG.1A, 3D memory device 100 may include a core region in which one or more,e.g., a pair of, source regions 22 extend along the x-direction. Asource structure may be formed in each source region 22. One or moreblock regions 21, in which a plurality of memory cells are formed, maybe between the pair of source regions 22. A memory block may be formedin each block region 21.

As shown in FIGS. 1A-1C, 3D memory device 100 may include a substrate102, and a stack structure 111 over substrate 102. In block regions 21,stack structure 111 may include a plurality of conductor layers 133 anda plurality of insulating layers 134 interleaved over substrate 102. Inblock region 21, stack structure 111 may also include a plurality ofchannel structures 110 extending through stack structure 111 intosubstrate 102 along a vertical direction (e.g., the z-direction). Eachchannel structure 110 may include an epitaxial portion at a bottomportion, a drain structure at a top portion, and a semiconductor channelbetween the epitaxial portion and the drain structure. The semiconductorchannel may include a memory film, a semiconductor layer, and in someembodiments, a dielectric core. The epitaxial portion may be in contactwith and conductively connected to substrate 102. The semiconductorchannel may be in contact with and conductively connected to the drainstructure and the epitaxial portion. A plurality of memory cells may beformed by the semiconductor channels and control conductor layers.

A source structure may be formed in source region 22 to extend along thex-direction. The source structure may include a plurality of sourceportions 104 each including a respective insulating structure and asource contact (detail not shown). Source portions 104 formed in onesource region 22 (e.g., within the same source structure) may be alignedalong the x-direction. The source structures may each extend verticallythrough stack structure 111 and contact substrate 102. A source voltagecan be applied to the memory cells through the source structure andsubstrate 102.

3D memory device 100 may include one or more support structures 120aligned along the x-direction and dividing a source structure into theplurality of source portions 104. In some embodiments, support structure120 includes interleaved a plurality of conductor portions 123 andinsulating portions 124 over substrate 102. Each support structure 120may be in contact with adjacent memory blocks (or block regions 21)along the y-direction, and in contact with insulating structures ofadjacent source portions 104 along the x-direction. In some embodiments,support structure 120 includes a spacer layer 125 over and surrounding(e.g., covering) conductor portions 123 and insulating portions 124.Spacer layer 125 may provide further insulation between conductorportions 123 and adjacent source portions 104. In some embodiments,support structure 120 provides support to 3D memory device 100 duringthe formation of the source structures and conductor layers 133.

3D memory device 100 may further include a connection layer 108 incontact with and conductively connected to at least two adjacent sourceportions 104, and a dielectric cap layer 115 partially coveringconnection layer 108. Dielectric cap layer 115 may cover portions ofconnection layer 108 that is in contact with and over source portions104, and expose the portions of connection layer 108 between adjacentsource portions 104. Contact plugs (not shown) for conductively applyinga source voltage can be formed on the exposed portions of connectionlayer 108. In some embodiments, connection layer 108 is over and incontact with all the source portions 104 in a source structure so thatsource voltage can be applied on all the source portions 104 of thesource structure through connection layer 108. The resistance of thesource structure can be reduced compared to applying the source voltageonto each source portion 104 using a respective contact plug. In someembodiments, dielectric cap layer 115 also covers at least a portion ofblock region 21. In some embodiments, dielectric cap layer 115 coversall channel structures 110 in block region 21. Contact plugs (not shown)for conductively applying a drain voltage can be formed extendingthrough dielectric cap layer 115 and form contact with channelstructures 110. For ease of illustration, coverage of dielectric caplayer 115 in block region 21 is not depicted. Details of each structureillustrated in FIGS. 1A-1C are described below.

Substrate 102 can include silicon (e.g., single crystalline silicon),silicon germanium (SiGe), gallium arsenide (GaAs), germanium (Ge),silicon on insulator (SOI), germanium on insulator (GOI), or any othersuitable materials. In some embodiments, substrate 102 is a thinnedsubstrate (e.g., a semiconductor layer), which was thinned by grinding,etching, chemical mechanical polishing (CMP), or any combinationthereof. In some embodiments, substrate 102 includes silicon.

Channel structures 110 may form an array and may each extend verticallyabove substrate 102. Channel structure 110 may extend through aplurality of pairs each including a conductor layer 133 and aninsulating layer 134 (referred to herein as “conductor/insulating layerpairs”). At least on one side along a horizontal direction (e.g.,x-direction and/or y-direction), stack structure 111 can include astaircase structure (not shown). The number of the conductor/insulatinglayer pairs in stack structure 111 (e.g., 32, 64, 96, or 128) determinesthe number of memory cells in 3D memory device 100. In some embodiments,conductor layers 133 and insulating layers 134 in stack structure 111are alternatingly arranged along the vertical direction in block regions21. Conductor layers 133 can include conductive materials including, butnot limited to, tungsten (W), cobalt (Co), copper (Cu), aluminum (Al),polysilicon, doped silicon, silicides, or any combination thereof.Insulating layers 134 can include dielectric materials including, butnot limited to, silicon oxide, silicon nitride, silicon oxynitride, orany combination thereof. In some embodiments, conductor layers 133 mayinclude a top conductor layer having a plurality of top select conductorlayers, and a bottom conductor layer having a plurality of bottom selectconductor layers. The top select conductor layers may function as thetop select gate electrodes, and the bottom select conductor layers mayfunction as the bottom select gate electrodes. Conductor layers 133between the top and bottom conductor layers may function as select gateelectrodes and form memory cells with intersecting channel structures110. Top select gate electrodes and bottom select gate electrodes canrespectively be applied with desired voltages to select a desired memoryblock/finger/page.

Channel structure 110 can include a semiconductor channel extendingvertically through stack structure 111. The semiconductor channel caninclude a channel hole filled with a channel-forming structure, e.g.,semiconductor materials (e.g., as a semiconductor layer) and dielectricmaterials (e.g., as a memory film). In some embodiments, thesemiconductor layer includes silicon, such as amorphous silicon,polysilicon, or single crystalline silicon. In some embodiments, thememory film is a composite layer including a tunneling layer, a memorylayer (also known as a “charge trap layer”), and a blocking layer. Theremaining space of the channel hole of semiconductor channel can bepartially or fully filled with a dielectric core including dielectricmaterials, such as silicon oxide. The semiconductor channel can have acylinder shape (e.g., a pillar shape). The dielectric core,semiconductor layer, the tunneling layer, the memory layer, and theblocking layer are arranged radially from the center toward the outersurface of the pillar in this order, according to some embodiments. Thetunneling layer can include silicon oxide, silicon oxynitride, or anycombination thereof. The memory layer can include silicon nitride,silicon oxynitride, silicon, or any combination thereof. The blockinglayer can include silicon oxide, silicon oxynitride, high dielectricconstant (high-k) dielectrics, or any combination thereof. In oneexample, the memory layer can include a composite layer of siliconoxide/silicon oxynitride (or silicon nitride)/silicon oxide (ONO).

In some embodiments, channel structure 110 further includes an epitaxialportion (e.g., a semiconductor plug) in the lower portion (e.g., at thelower end of bottom) of channel structure 110. As used herein, the“upper end” of a component (e.g., channel structure 110) is the endfarther away from substrate 102 in the vertical direction, and the“lower end” of the component (e.g., channel structure 110) is the endcloser to substrate 102 in the vertical direction when substrate 102 ispositioned in the lowest plane of 3D memory device 100. The epitaxialportion can include a semiconductor material, such as silicon, which isepitaxially grown from substrate 102 in any suitable directions. It isunderstood that in some embodiments, the epitaxial portion includessingle crystalline silicon, the same material as substrate 102. In otherwords, the epitaxial portion can include an epitaxially-grownsemiconductor layer grown from substrate 102. The epitaxial portion canalso include a different material than substrate 102. In someembodiments, the epitaxial portion includes at least one of silicon,germanium, and silicon germanium. In some embodiments, part of theepitaxial portion is above the top surface of substrate 102 and incontact with semiconductor channel. The epitaxial portion may beconductively connected to semiconductor channel. In some embodiments, atop surface of the epitaxial portion is located between a top surfaceand a bottom surface of a bottom insulating layer 134 (e.g., theinsulating layer at the bottom of stack structure 111).

In some embodiments, channel structure 110 further includes a drainstructure (e.g., channel plug) in the upper portion (e.g., at the upperend) of channel structure 110. The drain structure can be in contactwith the upper end of a semiconductor channel and may be conductivelyconnected to the semiconductor channel. The drain structure can includesemiconductor materials (e.g., polysilicon) or conductive materials(e.g., metals). In some embodiments, the drain structure includes anopening filled with Ti/TiN or Ta/TaN as an adhesion layer and tungstenas a conductor material. By covering the upper end of semiconductorchannel during the fabrication of 3D memory device 100, the drainstructure can function as an etch stop layer to prevent etching ofdielectrics filled in the semiconductor channel, such as silicon oxideand silicon nitride.

As shown in FIGS. 1A-1C, a source structure can be formed in sourceregion 22. The source structure, aligned along the x-direction, mayinclude a plurality of source portions 104 each including a sourcecontact in a respective insulating structure (not shown). Each sourceportion 104 may be in contact with and conductively connected tosubstrate 102. The insulating structure may insulate the respectivesource portion 104 (or respective source contact) from conductor layers133 in adjacent block regions 21. In some embodiments, the sourcecontacts in source portions 104 include at least one of polysilicon,aluminum, cobalt, copper, and silicides. The insulating structures caneach include a suitable dielectric material, such as one or more ofsilicon oxide, silicon nitride, and silicon oxynitride.

One or more support structures 120 may be distributed in a respectivesource structure along the x-direction. In some embodiments, the supportstructures 120 divides the respective source structure into a pluralityof source portions 104. In some embodiments, each source portion 104 isseparated from another source portion 104 by a support structure 120.Support structure 120, in contact with portions (e.g., memory blocks) ofstack structure 111 in adjacent block regions 21, may includeinterleaved a plurality of conductor portions 123 and a plurality ofinsulating portions 124. In some embodiments, each conductor portions123 is respectively in contact with corresponding conductor layers 133of the same level in adjacent block regions 21 (e.g., in adjacent memoryblocks), and each insulating portions 124 is respectively in contactwith corresponding insulating layers 134 of the same level in adjacentblock regions 21 (e.g., in adjacent memory blocks). In some embodiments,the top conductor portion 123 in support structure 120 is in contactwith (e.g., coplanar with) the top conductor layer 133 in adjacent blockregions 21. In some embodiments, the top insulating portion 124 insupport structure 120 is in contact with the top insulating layer 134 inadjacent block regions 21.

In some embodiments, support structure 120 includes a spacer layer 125covering and surrounding conductor portions 123 and insulating portions124. Spacer layer 125 may provide further insulation between conductorportions 123 and adjacent source portions 104. In some embodiments,spacer layer 125 (and the top insulating portion 124, if top conductorportion 123 is under top insulating portion 124) forms a layer ofdielectric material at the top portion of support structure 120 (e.g.,between connection layer 108 and top conductor portion 123). In someembodiments, a thickness t of the layer of dielectric material along thez-direction is greater than zero. In some embodiments, a top surface ofsource portion 104 is lower than a top surface of support structure 120along the z-direction. In some embodiments, the top surface of sourceportion 104 is lower than the top conductor portion 123 (e.g., the topand bottom surfaces of top conductor portion 123). In some embodiments,of the same source structure, top surfaces of all source portions 104are lower than top surfaces of all support structures 120. In someembodiments, a width of support structure 120 along the y-direction maynominally equal to a width of the source structure.

Each source structure may further include connection layer 108 over andin contact with at least two adjacent source portions 104. For example,connection layer 108 may be in contact with and conductively connectedto one or more pairs of adjacent source portions 104. Connection layer108 may be conductively connected to the source portions 104 with whichit's in contact. In some embodiments, connection layer 108 may partiallyor fully cover source portions 104 to which it's in contact with. Asshown in FIGS. 1A-1C, connection layer 108 may be over two adjacentsource portions 104 and the support structure 120 between the twoadjacent source portions 104. For example, connection layer 108 maypartially or fully cover two adjacent source portions 104 and thesupport structure 120 between the two adjacent source portions 104. Theportion of connection layer 108 in contact with and conductivelyconnected to source portion 104 may be referred to as a first portion108-1 of connection layer 108. The portion of connection layer 108 incontact with support structure 120 may be referred to as a secondportion 108-2 of connection layer 108. In some embodiments, secondportion 108-2 of connection layer 108 may be in contact with andconductively connected to a pair of first portions 108-1, e.g., adjacentfirst portions 108-1 on both sides of second portion 108-2 along thex-direction. In some embodiments, connection layer 108 may include aplurality of first portions 108-1 and a plurality of second portions108-2 in contact with and conductively connected to one another alongthe x-direction. In some embodiments, top surfaces of second portions108-2 of connection layer 108 may be higher than top surfaces of firstportions 108-1 of connection layer 108.

In some embodiments, connection layer 108 may include more than onesegment, each including at least one second portion 108-2 and aplurality of first portions 108-1 in contact with one another. Eachsegment may be over and in contact with one or more pairs of adjacentsource portions 104 of the source structure. For example, the one ormore pairs of adjacent source portions 104, connected to differentsegments of connection layer 108, may be separated by one or more sourceportions 104 that are not in contact with connection layer 108. Thespecific number of segments in connection layer 108 should be determinedbased on the design and/or fabrication of 3D memory device 100 andshould not be limited by the embodiments of the present disclosure. Insome embodiments, connection layer 108 may be over and in contact withall source portions 104 in the respective source structure. A sourcevoltage may be applied on second portions 108-2 of the source structureso the all source portions 104 connected to connection layer 108 can beapplied with the source voltage.

In some embodiments, a width of connection layer 108 (or its segments,if any) along the y-direction may vary, depending on the design and/orfabrication process of 3D memory device 100. In some embodiments,connection layer 108 may partially cover the source portions 104underneath. That is, the width of connection layer 108 along they-direction is equal to or less than the width of the source structurealong the y-direction. In some embodiments, dielectric cap layer 115 maycover first portions 108-1 of connection layer 108 and expose secondportions 108-2 of connection layer. A width d1 of second portion 108-2of connection layer 108 may be less than or equal to a width d2 ofdielectric cap layer 115 along the y-direction. In some embodiments,width d1 is less than width d2 so dielectric cap layer 115 can insulatesecond portion 108-2 from surroundings structures and/or devices alonglateral directions (e.g., in the x-y plane). In some embodiments,conductive plugs (now shown, for applying a source voltage on connectionlayer 108) are formed on second portions 108-2. In some embodiments,dielectric cap layer 115 may be partially located in block regions 21.In some embodiments, dielectric cap layer 115 covers all channelstructures 110 in block region 21. Contact plugs (not shown) forconductively applying a drain voltage can subsequently be formedextending through dielectric cap layer 115 and form contact with channelstructures 110.

In some embodiments, spacer layer 125 includes one or more of siliconoxide, silicon nitride, and/or silicon oxynitride. In some embodiments,conductor portions 123 include the same material as conductor layers 133in adjacent block regions 21, and insulating portions 124 include thesame material as insulating layers 134 in adjacent block regions 21. Forexample, conductor portions 123 may include one or more of tungsten,aluminum, cobalt, copper, polysilicon, and silicides, and insulatingportions 124 may include one or more of silicon oxide, silicon nitride,and silicon oxynitride. In some embodiments, connection layer 108includes one or more of tungsten, aluminum, cobalt, copper, polysilicon,and silicides. In some embodiments, source portion 104 includespolysilicon, and connection layer 108 includes tungsten. In someembodiments, dielectric cap layer 115 includes silicon oxide. In someembodiments, 3D memory device 100 includes an adhesion layer (notshown), e.g., TiN, between source portion 104 (or the source contact ofsource portion 104) and connection layer 108 to improve the adhesionand/or conductivity between source portion 104 and connection layer 108.In some embodiments, 3D memory device 100 includes another adhesionlayer (not shown), e.g., TiN, between the respective insulatingstructure of source portion 104 and support structure 120 (e.g., spacerlayer 125) to improve the adhesion between the insulating structure andsupport structure 120.

3D memory device 100 can be part of a monolithic 3D memory device. Theterm “monolithic” means that the components (e.g., the peripheral deviceand memory array device) of the 3D memory device are formed on a singlesubstrate. For monolithic 3D memory devices, the fabrication encountersadditional restrictions due to the convolution of the peripheral deviceprocessing and the memory array device processing. For example, thefabrication of the memory array device (e.g., NAND channel structures)is constrained by the thermal budget associated with the peripheraldevices that have been formed or to be formed on the same substrate.

Alternatively, 3D memory device 100 can be part of a non-monolithic 3Dmemory device, in which components (e.g., the peripheral device andmemory array device) can be formed separately on different substratesand then bonded, for example, in a face-to-face manner. In someembodiments, the memory array device substrate (e.g., substrate 102)remains as the substrate of the bonded non-monolithic 3D memory device,and the peripheral device (e.g., including any suitable digital, analog,and/or mixed-signal peripheral circuits used for facilitating theoperation of 3D memory device 100, such as page buffers, decoders, andlatches; not shown) is flipped and faces down toward the memory arraydevice (e.g., NAND memory strings) for hybrid bonding. It is understoodthat in some embodiments, the memory array device substrate (e.g.,substrate 102) is flipped and faces down toward the peripheral device(not shown) for hybrid bonding, so that in the bonded non-monolithic 3Dmemory device, the memory array device is above the peripheral device.The memory array device substrate (e.g., substrate 102) can be a thinnedsubstrate (which is not the substrate of the bonded non-monolithic 3Dmemory device), and the back-end-of-line (BEOL) interconnects of thenon-monolithic 3D memory device can be formed on the backside of thethinned memory array device substrate.

FIG. 8A illustrates an exemplary pattern set 800 for forming the etchmasks used in the fabrication process. FIG. 8B illustrates an enlargedview of a unit 850 of the pattern set. Patterns in pattern set 800 maybe used in different stages of a fabrication process to form 3D memorydevice 100. In various embodiments, depending on the types ofphotoresist used in the patterning processes, patterns in pattern set800 may each be a part of an etch mask or a pattern for determining anetch mask. For example, if a negative photoresist is used forpatterning, the patterns in pattern set 800 may be used as parts of etchmasks; if a positive photoresist is used for patterning, the patterns inpattern set 8700 may be complementary patterns for determining the etchmasks. It should be noted that the shapes, dimensions, and ratios shownin FIGS. 8A and 8B are for illustrative purposes and are not to scale.

As shown in FIG. 8A, pattern set 800 includes patterns 802, 804, and806. Specifically, pattern 802 may be used for patterning slit openingsof a slit structure, in which a source structure is formed. Pattern 804may be used for patterning connection layer 108, or the secondportion(s) of connection layer 108. Pattern 806 may be used for formingcontact plugs in contact with and conductively connected to connectionlayer 108 and a peripheral circuit. Pattern set 800 may include aplurality of repeating units, e.g., 850, for the formation of supportstructure 120, the slit openings, and connection layer 108. The actualdimensions of patterns 802, 804, and 806 may be determined based on thefabrication processes and should not be limited by the embodiments ofthe present disclosure.

FIG. 8B illustrates a repeating unit 850 that shows the details, e.g.,coverage, of each pattern. In some embodiments, an etch maskcorresponding to pattern 802 is used to form the slit openings andsupport structures 120. A width W1 of pattern 802 may be nominally equalto a lateral dimension of the respective slit opening and supportstructure 120 along the y-direction. A distance D1 between adjacentportions of pattern 802 may be nominally equal to the lateral dimensionof support structure 120 along the x-direction. In some embodiments, anetch mask corresponding to pattern 804 is used to form second portion108-2 of connection layer. A length D2 of pattern 804 along thex-direction may be nominally equal to the lateral dimension of secondportion 108-2 of connection layer along the x-direction, and a width W2of pattern 804 along the y-direction may be nominally equal to thelateral dimension of second portion 108-2 of connection layer along they-direction. Length D2 may be equal to or greater than distance D1 sosecond portion 108-2 of connection layer can be in contact with firstportion 108-1 over the adjacent source portions 104. In someembodiments, W2<W1, and D1<D2. The sequence to apply the patterns may bedescribed in the fabrication process for forming 3D memory device 100below.

FIGS. 2-7 illustrate a fabrication process to form 3D memory device 100,and FIGS. 10A and 10B illustrate a flowchart 1000 of the fabricationprocess, according to some embodiments. FIG. 10B is a continuation ofFIG. 10A. For ease of illustration, FIGS. 8A and 8B are illustratedtogether with FIGS. 2-7 to describe the fabrication process.

At the beginning of the process, at operation 1002, a plurality ofchannel structures are formed in a stack structure. FIGS. 2A and 2Billustrate a corresponding structure.

As shown in FIGS. 2A and 2B, a plurality of channel structures 210 areformed in a stack structure 211. Stack structure 211 may have adielectric stack of interleaved sacrificial material layers 223 andinsulating material layers 224 formed over a substrate 102. Sacrificialmaterial layers 223 may be used for subsequent formation of conductorlayers and conductor portions. Insulating material layers 224 may beused for subsequent formation of insulating layers and insulatingportions. In some embodiments, stack structure 211 includes a firstdielectric cap layer (not shown) on the top surface of stack structure211. 3D memory device 100 may include a channel region for formingchannel structures 210. The channel region may include a plurality ofsource regions 22 and a block region 21 between adjacent source regions22.

Stack structure 211 may have a staircase structure. The staircasestructure can be formed by repetitively etching a material stack thatincludes a plurality of interleaved sacrificial material layers andinsulating material layers using an etch mask, e.g., a patterned PRlayer over the material stack. The interleaved sacrificial materiallayers and the insulating material layers can be formed by alternatinglydepositing layers of sacrificial material and layers of insulatingmaterial over substrate 102 until a desired number of layers is reached.The sacrificial material layers and insulating material layers can havethe same or different thicknesses. In some embodiments, a sacrificialmaterial layer and the underlying insulating material layer are referredto as a dielectric pair. In some embodiments, one or more dielectricpairs can form one level/staircase. During the formation of thestaircase structure, the PR layer is trimmed (e.g., etched incrementallyand inwardly from the boundary of the material stack, often from alldirections) and used as the etch mask for etching the exposed portion ofthe material stack. The amount of trimmed PR can be directly related(e.g., determinant) to the dimensions of the staircases. The trimming ofthe PR layer can be obtained using a suitable etch, e.g., an isotropicdry etch such as a wet etch. One or more PR layers can be formed andtrimmed consecutively for the formation of the staircase structure. Eachdielectric pair can be etched, after the trimming of the PR layer, usingsuitable etchants to remove a portion of both the sacrificial materiallayer and the underlying insulating material layer. The etchedsacrificial material layers and insulating material layers may formsacrificial material layers 223 and insulating material layers 224. ThePR layer can then be removed.

The insulating material layers and sacrificial material layers may havedifferent etching selectivities during the subsequent gate-replacementprocess. In some embodiments, the insulating material layers and thesacrificial material layers include different materials. In someembodiments, the insulating material layers include silicon oxide, andthe deposition of insulating material layers include one or more ofchemical vapor deposition (CVD), atomic layer deposition (ALD), andphysical vapor deposition (PVD). In some embodiments, the sacrificialmaterial layers include silicon nitride, and the deposition ofinsulating material layers include one or more of CVD, PVD, and ALD. Insome embodiments, the etching of the sacrificial material layers and theinsulating material layers include one or more suitable etching process,e.g., dry etch and/or wet etch.

A plurality of channel structures 210 can be formed in block region 21before or after the formation of the support structures. Forillustrative purposes, in embodiments of the present disclosure, channelstructures 210 are formed prior to the support structures. To formchannel structures 210, a plurality of channel holes may be formedextending vertically through stack structure 211. In some embodiments, aplurality of channel holes are formed through the interleavedsacrificial material layers 223 and insulating material layers 224. Theplurality of channel holes may be formed by performing an anisotropicetching process, using an etch mask such as a patterned PR layer, toremove portions of stack structure 211 and expose substrate 202. In someembodiments, a plurality of channel holes are formed in each blockregion 21. A recess region may be formed at the bottom of each channelhole to expose a top portion of substrate 202 by the same etchingprocess that forms the channel hole above substrate 202 and/or by aseparate recess etching process. In some embodiments, a semiconductorplug is formed at the bottom of each channel hole, e.g., over the recessregion. The semiconductor plug may be formed by an epitaxial growthprocess and/or a deposition process. In some embodiments, thesemiconductor plug is formed by epitaxial growth and is referred to asthe epitaxial portion. Optionally, a recess etch (e.g., dry etch and/orwet etch) may be performed to remove excess semiconductor material onthe sidewall of the channel hole and/or control the top surface of theepitaxial portion at a desired position. In some embodiments, the topsurface of the epitaxial portion is located between the top and bottomsurfaces of the bottom insulating material layer 224.

In some embodiments, the channel holes are formed by performing asuitable etching process, e.g., an anisotropic etching process (e.g.,dry etch) and/or an isotropic etching process (wet etch). In someembodiments, the epitaxial portion includes single crystalline siliconis formed by epitaxially grown from substrate 202. In some embodiments,the epitaxial portion includes polysilicon formed by a depositionprocess. The formation of epitaxially-grown epitaxial portion caninclude, but not limited to, vapor-phase epitaxy (VPE), liquid-phaseepitaxy (LPE), molecular-beam epitaxy (MPE), or any combinationsthereof. The formation of the deposited epitaxial portion may include,but not limited by, CVD, PVD, and/or ALD.

In some embodiments, a semiconductor channel is formed over and incontact with the epitaxial portion in the channel hole. Semiconductorchannel can include a channel-forming structure that has a memory film(e.g., including a blocking layer, a memory layer, and a tunnelinglayer), a semiconductor layer formed above and connecting the epitaxialportion, and a dielectric core filling up the rest of the channel hole.In some embodiments, memory film is first deposited to cover thesidewall of the channel hole and the top surface of the epitaxialportion, and a semiconductor layer is then deposited over memory filmand above epitaxial portion. The blocking layer, memory layer, andtunneling layer can be subsequently deposited in this order using one ormore thin film deposition processes, such as ALD, CVD, PVD, any othersuitable processes, or any combination thereof, to form memory film. Thesemiconductor layer can then be deposited on the tunneling layer usingone or more thin film deposition processes, such as ALD, CVD, PVD, anyother suitable processes, or any combination thereof. In someembodiments, a dielectric core is filled in the remaining space of thechannel hole by depositing dielectric materials after the deposition ofthe semiconductor layer, such as silicon oxide.

In some embodiments, a drain structure is formed in the upper portion ofeach channel hole. In some embodiments, parts of memory film,semiconductor layer, and dielectric core on the top surface of stackstructure 211 and in the upper portion of each channel hole can beremoved by CMP, grinding, wet etching, and/or dry etching to form arecess in the upper portion of the channel hole so that a top surface ofsemiconductor channel may be between the top surface and the bottomsurface of the first dielectric cap layer. Drain structure then can beformed by depositing conductive materials, such as metals, into therecess by one or more thin film deposition processes, such as CVD, PVD,ALD, electroplating, electroless plating, or any combination thereof. Achannel structure 210 is thereby formed. A plurality of memory cells maysubsequently be formed by the intersection of the semiconductor channelsand the control conductor layers. Optionally, a planarization process,e.g., dry/wet etch and/or CMP, is performed to remove any excessmaterial on the top surface of stack structure 211.

Referring back to FIG. 10A, after the formation of the channelstructures, method 1000 proceeds to operation 1004, in which portions ofthe stack structure are removed to form a slit structure and at leastone initial support structure dividing the slit structure into aplurality of slit opening (Operation 1004). The at least one initialsupport structure each has interleaved a plurality of sacrificialportions and a plurality of insulating portions between adjacent slitopenings. FIGS. 3A and 3B illustrate a corresponding structure.

As shown in FIGS. 3A and 3B, portions of stack structure 211 in sourceregion 22, are removed to form a slit structure that has a plurality ofslit openings 306, and at least one initial support structure. The slitstructure may expose substrate 102. Pattern 802 may be used forpatterning stack structure 211 and form the slit structure and theinitial support structures. That is, portions of stack structure 211 insource region 22 are removed to form slit openings 306. The un-etchedportions of stack structure 211 in source region 22 may form interleavedsacrificial portions and insulating portions 324, forming initialsupport structure. Sacrificial portions and insulating portions 324 mayeach be in contact with the sacrificial layers and insulating layers ofthe same level in adjacent block regions 21. In some embodiments, slitopenings 306 may expose substrate 202 and interleaved sacrificial layersand insulating layers in adjacent block regions 21. In some embodiments,along the y-direction, a width of the initial support structure maynominally equal to a width of the slit structure. A suitable anisotropicetching process, e.g., dry etch, can be performed to form slit openings306 and initial support structure.

Referring back to FIG. 10A, after the formation of the initial supportstructure and the slit structure, method 1000 proceeds to operation1006, in which the sacrificial portions in each initial supportstructure and the sacrificial layers in each block region are replacedwith conductor portions and conductor layers, forming at least onesupport structure and a plurality of memory blocks. FIGS. 3A and 3Billustrate a corresponding structure.

As shown in FIGS. 3A and 3B, the sacrificial portions in each initialsupport structure are replaced with a plurality of conductor portions323. The sacrificial layers in each block region 21 are replaced with aplurality of conductor layers (referring back to conductor layers 133FIG. 1C). An isotropic etching process, e.g., wet etch, can be performedto remove the sacrificial portions and sacrificial layers through theslit structures (or slit openings 306). A plurality of lateral recessesmay be formed in each block region 21 by the removal of the sacrificiallayers, and a plurality of recess portions may be formed in each initialsupport structure by the removal of the sacrificial portions. Aconductor material may then be deposited to fill up the lateral recessesand recess portions, forming the plurality of conductor layers in eachblock region and the plurality of conductor portions 323 in each initialsupport structure. Accordingly, support structure 320, havinginterleaved conductor portions 323 and insulating portions 324, may beformed.

Referring back to FIG. 10A, after the formation of the conductorportions and conductor layers, optionally, method 1000 proceeds tooperation 1008, in which a spacer layer is formed over the interleavedconductor portions and insulating portions. FIGS. 3A and 3B illustrate acorresponding structure.

In some embodiments, a spacer layer 325 is formed to surroundinterleaved conductor portions 323 and insulating portions 324. Spacerlayer 325 may cover interleaved conductor portions 323 and insulatingportions 324 on the top surface and on the side surfaces that are incontact with slit openings 306. In some embodiments, spacer layer 325 isdeposited by at least one of CVD, PVD, and ALD. In some embodiments,spacer layer 325 undergoes a recess etch such that spacer layer 325 hasdesired a thickness.

Referring back to FIG. 10A, after the formation of the supportstructure, method 1000 proceeds to operation 1010, in which a sourcestructure having a plurality of source portions are each formed in arespective slit opening of the slit structure. FIGS. 4A and 4Billustrate a corresponding structure.

As shown in FIGS. 4A and 4B, a source structure is formed in the slitstructure. The source structure may include a plurality of sourceportions 404, each having an insulating structure in the respective slitopening 306 of the slit structure and a source contact in eachinsulating structure. Optionally, an adhesion layer (not shown) isdeposited over the top surface and/or sidewalls of support structure 320before the formation of the source structure. In some embodiments, theinsulating structure includes silicon oxide and the source contactsinclude polysilicon. The insulating structure and source contacts mayeach be deposited by one or more of CVD, PVD, ALD, and sputtering. Arecess etching process may be performed on the insulating structure toexpose substrate 202 so the respective source contact can be in contactwith substrate 202. In some embodiments, the adhesion layer includes TiNand is deposited by one or more of CVD, PVD, ALD, and electroplating. Insome embodiments, top surfaces of source portions 104 may be lower thana top surface of support structure 320. Optionally, a recess etchingprocess may be performed to etch back source portions 404 to formsufficient space in slit openings 306 for the formation of theconnection layer.

Referring back to FIG. 10B, after the formation of the source portions,method 1000 proceeds to operation 1012, in which a plurality of firstportions of a connection layer is formed to each be over a respectivesource portion. FIGS. 4A and 4B illustrate a corresponding structure.

As shown in FIGS. 4A and 4B, a first portion 408-1 of connection layer408 is deposited over a respective source portion 404 (or the sourcecontact of source portion 404). First portion 408-1 may partially orfully cover the respective source portion 404. In some embodiments,first portions 408-1 of connection layer 408 fill up slit openings 306.Optionally, an adhesion layer (not shown) is deposited over the topsurface of source portions 404 before the formation of first portion408-1 of connection layer 408. In some embodiments, first portions 408-1of connection layer 408 includes a conductive material that includes oneor more of tungsten, aluminum, copper, cobalt, polysilicon, andsilicides. In some embodiments, source portions 404 includes polysiliconand first portions 408-1 of connection layer 408 include tungsten.Optionally, a planarization process, e.g., CMP and/or recess etch, isperformed to remove any excess material over first portions 408-1 ofconnection layer 408 and support structures 320. In some embodiments,the top surfaces of support structures 320 and first portions 408-1 ofconnection layer 408 may be coplanar in the x-y plane.

Referring back to FIG. 10B, after the formation of the first portions ofthe connection layer, method 1000 proceeds to operation 1014, in which adielectric cap layer is formed over the first portions of the connectionlayer and exposing at least two adjacent first portions of theconnection layer. FIGS. 5A, 5B, 6A, and 6B illustrate correspondingstructures.

As shown in FIGS. 5A and 5B, a dielectric cap layer 515 is formed overeach source structure. In some embodiments, dielectric cap layer 515covers a pair of adjacent first portions 408-1 of connection layer 408and support structure 320 in between. In some embodiments, dielectriccap layer 515 also covers areas outside of source regions 22, such asblock regions 21. The area covered by dielectric cap layer 515 may bedetermined based on the coverage of the subsequently-formed secondportions 408-2 of connection layer 408. In some embodiments, the areacovered by dielectric cap layer 515 may be greater than the area ofsecond portions 408-2 of connection layer 408 along the x-y plane toinsulate connection layer 408 from other parts of stack structure 211except for source portions 404. Dielectric cap layer 515 may be formedby depositing a suitable dielectric material such as silicon oxide tocover first portions 408-1 and support structures 320. In someembodiments, dielectric cap layer 515 covers all channel structures 210in block region 21. Dielectric cap layer 515 may be deposited by one ormore of CVD, PVD, and ALD.

As shown in FIGS. 6A and 6B, dielectric cap layer 515 is patterned toform at least one opening 614 which exposes at least a pair of twoadjacent first portions 408-1 of connection layer 408. In someembodiments, opening 614 also exposes the support structure 320 betweenthe pair of adjacent first portions 408-1. In some embodiments, supportstructure 320 (or the dielectric material on the top portion of supportstructure 320) is partially removed for the formation of opening 614. Insome embodiments, dielectric cap layer 515 exposes all the supportstructures 320 and all pairs of adjacent first portions 408-1 ofconnection layer 408. Pattern 804 may be used for patterning opening614. The formation of opening 614 may include a photolithography processand a suitable etching process, e.g., dry etch and/or wet etch. In someembodiments, along the y-direction, a width d2 of dielectric cap layer515 is greater than a width d1 of first portions 408-1 of connectionlayer 408 (or the width of opening 614).

Referring back to FIG. 10B, after the formation of the dielectric caplayer, method 1000 proceeds to operation 1016, in which a second portionof the connection layer is formed over a support structure and incontact with and conductively connected to a pair of adjacent firstportions of the connection layer. FIGS. 7A and 7B illustrate acorresponding structure.

As shown in FIGS. 7A and 7B, a second portion 408-2 of connection layer408 is formed in dielectric cap layer 515. Second portion 408-2 ofconnection layer 408 may be in contact with and conductively connectedto the exposed pair of two adjacent first portions 408-1 of connectionlayer 408, forming connection layer 408. The pair of two adjacent firstportions 408-1 of connection layer 408 may be positioned on both sidesof the support structure 320 between the two adjacent first portions408-1 of connection layer 408. In some embodiments, a plurality ofsecond portions 408-2 of connection layer 408 are formed in a pluralityof openings 614 to be in contact with and conductively connected to aplurality of pairs, e.g., all pairs, of adjacent first portions 408-1 ofconnection layer 408. Second portion 408-2 of connection layer 408 maybe formed by depositing a suitable conductive material that fills upopening 614. The conductive material may fully or partially coversupport structure 320 and the exposed portions of the pair of adjacentfirst portions 408-1 of connection layer 408. The conductive materialmay include one or more of tungsten, aluminum, copper, cobalt,polysilicon, and silicides. In some embodiments, the conductive materialincludes tungsten and is deposited by one or more of CVD, PVD, and ALD.Optionally, a planarization process, e.g., CMP and/or recess etch, isperformed to remove any excess material over second portion 408-2 ofconnection layer 408.

According to the embodiments of the present disclosure, a 3D memorydevice includes a memory stack over a substrate, a plurality of channelstructures, a source structure, and a support structure. The memorystack includes interleaved a plurality of conductor layers and aplurality of insulating layers. The plurality of channel structuresextend vertically in the memory stack. The source structure includes aplurality of source portions and extending in the memory stack. Thesupport structure is between adjacent ones of the source portions andhas a plurality of interleaved conductor portions and insulatingportions. A top one of the conductor portions is in contact with a topone of the conductor layers. Adjacent ones of the source portions areconductively connected to one another.

In some embodiments, the source structure further includes a connectionlayer in contact with and conductively connected to the adjacent ones ofthe source portions, the connection layer being a conductive layer.

In some embodiments, the connection layer includes at least one oftungsten, cobalt, aluminum, copper, silicides, or polysilicon.

In some embodiments, the connection layer is positioned over each of theadjacent ones of the source portions.

In some embodiments, the connection layer is over the support structure.

In some embodiments, the support structure is in contact with memoryblocks adjacent to the source structure.

In some embodiments, each of the conductor portions is in contact withconductor layers of the same level in the memory blocks and each of theinsulating portions is in contact with insulating layers of the samelevel in the memory blocks.

In some embodiments, the conductor portions and the conductor layersinclude the same materials, and the insulating portions and theinsulating layers include the same materials.

In some embodiments, the top one of the conductor portions of thesupport structure is higher than top surfaces of the adjacent ones ofthe source portions.

In some embodiments, the 3D memory device further includes a cap layerover the source structure. The cap layer covers a pair of first portionsof the connection layer that are over the adjacent ones of the sourceportions and exposes a second portion of the connection layer that isover the support structure.

In some embodiments, a top surface of the second portion of theconnection layer is higher than top surfaces of the pair of firstportions of the connection layer.

In some embodiments, the connection layer is over and in contact witheach of the plurality of source contacts.

In some embodiments, along a lateral direction perpendicular to anotherlateral direction along which the source structure extends, a width ofthe connection layer is equal to or less than a width of the sourcestructure.

In some embodiments, the support structure includes a spacer layer incontact with and surrounding the interleaved plurality of conductorportions and insulating portions.

In some embodiments, the 3D memory device further includes an adhesionlayer between each of the source portions and the adjacent supportstructure, and between the source portion and the connection layer incontact with the source portion.

In some embodiments, the adhesion layer includes titanium nitride.

According to embodiments of the present disclosure, a 3D memory deviceincludes a memory stack, a plurality of channel structures, a sourcestructure, and a support structure. The memory stack has a plurality ofmemory blocks over a substrate, each of the memory blocks havinginterleaved a plurality of conductor layers and a plurality ofinsulating layers. The plurality of channel structures extend verticallyin the memory blocks. The source structure extend between adjacentmemory blocks. The support structure is in contact with the sourcestructure and having a plurality of interleaved conductor portions andinsulating portions. Adjacent memory blocks are in contact with eachother through the support structure. A top one of the conductor portionsis in contact with a top one of the conductor layers in each of theadjacent memory blocks.

In some embodiments, the source structure includes a plurality of sourceportions, adjacent ones of the source portions are conductivelyconnected to one another.

In some embodiments, the source structure further includes a connectionlayer in contact with and conductively connected to the adjacent ones ofthe source portions, the connection layer being a conductive layer.

In some embodiments, the connection layer includes at least one oftungsten, cobalt, aluminum, copper, silicides, or polysilicon.

The 3D memory device of claim 19 or 20, wherein the connection layer ispositioned over each of the adjacent ones of the source portions and thesupport structure.

In some embodiments, each of the conductor portions is in contact withconductor layers of the same level in the adjacent memory blocks andeach of the insulating portions is in contact with insulating layers ofthe same level in the adjacent memory blocks.

In some embodiments, the conductor portions and the conductor layersinclude the same materials, and the insulating portions and theinsulating layers include the same materials.

In some embodiments, the top one of the conductor portions of thesupport structure is higher than top surfaces of the adjacent ones ofthe source portions.

In some embodiments, the 3D memory device further includes a cap layerover the source structure. The cap layer covers a pair of first portionsof the connection layer that are over the adjacent ones of the sourceportions and exposes a second portion of the connection layer that isover the support structure.

In some embodiments, a top surface of the second portion of theconnection layer is higher than top surfaces of the pair of firstportions of the connection layer.

In some embodiments, the connection layer is over and in contact witheach of the plurality of source contacts.

In some embodiments, along a lateral direction perpendicular to anotherlateral direction along which the source structure extends, a width ofthe connection layer is equal to or less than a width of the sourcestructure.

In some embodiments, the support structure includes a spacer layer incontact with and surrounding the interleaved plurality of conductorportions and insulating portions.

In some embodiments, the 3D memory device further includes an adhesionlayer between each of the source portions and the adjacent supportstructure, and between the source portion and the connection layer incontact with the source portion.

In some embodiments, the adhesion layer includes titanium nitride.

According to embodiments of the present disclosure, a method for forminga 3D memory device includes the following operations. First, a slitstructure and a support structure are formed in a stack structure havinginterleaved a plurality of sacrificial material layers and a pluralityof insulating material layers, the initial support structure betweenadjacent slit openings of the slit structure. A source structure isformed to include a source portion in each of the slit openings. A pairof first portions of a connection layer is formed in contact with andconductively connected to the source portion. A second portion of theconnection layer is formed in contact with and conductively to the pairof first portions of the connection layer.

In some embodiments, forming the slit structure and the supportstructure include removing portions of the stack structure to form aplurality of slit openings and an initial support structure betweenadjacent ones of the slit openings, and forming a plurality of conductorportions in the initial support structure through the slit structure.

In some embodiments, forming the plurality of conductor portionsincludes removing, through the plurality of slit openings, the pluralityof sacrificial portions in the initial support structure to form aplurality of recess portions. In some embodiments, forming the pluralityof conductor portions also includes depositing a conductor material tofill up the plurality of recess portions to form the plurality ofconductor portions.

In some embodiments, the method further includes forming a plurality ofconductor layers in a memory block in the stack structure in the sameoperations that form the plurality of conductor portions. The pluralityof conductor layers are formed by removing, through the plurality ofslit openings, a plurality of sacrificial layers in the block to form aplurality of lateral recesses. The plurality of conductor layers arealso formed by depositing the conductor material to fill up theplurality of lateral recesses to form the plurality of conductor layers.

In some embodiments, forming the support structure further includesforming a spacer layer over the conductor portions and the insulatingportions.

In some embodiments, the method further includes forming a cap layerover the pair of first portions of the connection layer, forming anopening in the cap layer to expose the pair of first portions of theconnection layer, and forming the second portion in the opening to be incontact with and conductively connected to the pair of first portions.

In some embodiments, the method further includes exposing the supportstructure in the opening such that the second portion of the connectionlayer is over the support structure.

In some embodiments, forming the pair of first portions of theconnection layer includes depositing a conductive material over thesource portions. In some embodiments, forming the second portion of theconnection layers includes depositing the conductive material to fill upthe opening in the cap layer.

In some embodiments, the method further includes depositing an adhesionlayer between the pairs of first portions of the connection layer andthe cap layer.

In some embodiments, forming the source structure includes depositing atleast one of cobalt, aluminum, copper, silicides, or polysilicon in theslit openings.

In some embodiments, the method further includes depositing anotheradhesion layer between the source structure and the support structure.

The foregoing description of the specific embodiments will so reveal thegeneral nature of the present disclosure that others can, by applyingknowledge within the skill of the art, readily modify and/or adapt forvarious applications such specific embodiments, without undueexperimentation, without departing from the general concept of thepresent disclosure. Therefore, such adaptations and modifications areintended to be within the meaning and range of equivalents of thedisclosed embodiments, based on the teaching and guidance presentedherein. It is to be understood that the phraseology or terminologyherein is for the purpose of description and not of limitation, suchthat the terminology or phraseology of the present specification is tobe interpreted by the skilled artisan in light of the teachings andguidance.

Embodiments of the present disclosure have been described above with theaid of functional building blocks illustrating the implementation ofspecified functions and relationships thereof. The boundaries of thesefunctional building blocks have been arbitrarily defined herein for theconvenience of the description. Alternate boundaries can be defined solong as the specified functions and relationships thereof areappropriately performed.

The Summary and Abstract sections may set forth one or more but not allexemplary embodiments of the present disclosure as contemplated by theinventor(s), and thus, are not intended to limit the present disclosureand the appended claims in any way.

The breadth and scope of the present disclosure should not be limited byany of the above-described exemplary embodiments, but should be definedonly in accordance with the following claims and their equivalents.

What is claimed is:
 1. A three-dimensional (3D) memory device,comprising: a memory stack over a substrate, the memory stack comprisinginterleaved a plurality of conductor layers and a plurality ofinsulating layers; a plurality of channel structures extendingvertically in the memory stack; a source structure comprising aplurality of source portions and extending in the memory stack; and asupport structure between adjacent ones of the source portions andcomprising a plurality of interleaved conductor portions and insulatingportions, wherein a top one of the conductor portions is in contact withand conductively connected to a top one of the conductor layers, andadjacent ones of the source portions are conductively connected to oneanother.
 2. The 3D memory device of claim 1, wherein the sourcestructure further comprises a connection layer in contact with andconductively connected to the adjacent ones of the source portions, theconnection layer being a conductive layer.
 3. The 3D memory device ofclaim 2, wherein the connection layer comprises at least one oftungsten, cobalt, aluminum, copper, silicides, or polysilicon.
 4. The 3Dmemory device of claim 2, wherein the connection layer is positionedover each of the adjacent ones of the source portions.
 5. The 3D memorydevice of claim 4, wherein the connection layer is over the supportstructure.
 6. The 3D memory device of claim 4, wherein the supportstructure is in contact with memory blocks adjacent to the sourcestructure.
 7. The 3D memory device of claim 6, wherein each of theconductor portions is in contact with conductor layers of a same levelin the memory blocks and each of the insulating portions is in contactwith insulating layers of the same level in the memory blocks; and theconductor portions and the conductor layers comprise the same materials,and the insulating portions and the insulating layers comprise the samematerials.
 8. The 3D memory device of claim 1, wherein the top one ofthe conductor portions of the support structure is higher than topsurfaces of the adjacent ones of the source portions.
 9. The 3D memorydevice of claim 2, further comprising a cap layer over the sourcestructure, wherein: the cap layer covers a pair of first portions of theconnection layer that are over the adjacent ones of the source portionsand exposes a second portion of the connection layer that is over thesupport structure; and a top surface of the second portion of theconnection layer is higher than top surfaces of the pair of firstportions of the connection layer.
 10. The 3D memory device of claim 2,wherein the connection layer is over and in contact with each of theplurality of source contacts.
 11. A three-dimensional (3D) memorydevice, comprising: a memory stack comprising a plurality of memoryblocks over a substrate, each of the memory blocks comprisinginterleaved a plurality of conductor layers and a plurality ofinsulating layers; a plurality of channel structures extendingvertically in the memory blocks; a source structure extending betweenadjacent memory blocks; and a support structure in contact with thesource structure and comprising a plurality of interleaved conductorportions and insulating portions, wherein adjacent memory blocks are incontact with each other through the support structure, and a top one ofthe conductor portions is in direct contact with a top one of theconductor layers in each of the adjacent memory blocks.
 12. The 3Dmemory device of claim 11, wherein the source structure comprises aplurality of source portions, adjacent ones of the source portions areconductively connected to one another.
 13. The 3D memory device of claim12, wherein the source structure further comprises a connection layer incontact with and conductively connected to the adjacent ones of thesource portions, the connection layer being a conductive layer.
 14. The3D memory device of claim 13, wherein the connection layer comprises atleast one of tungsten, cobalt, aluminum, copper, silicides, orpolysilicon.
 15. The 3D memory device of claim 14, wherein theconnection layer is positioned over each of the adjacent ones of thesource portions and the support structure.
 16. The 3D memory device ofclaim 11, wherein each of the conductor portions is in contact withconductor layers of a same level in the adjacent memory blocks and eachof the insulating portions is in contact with insulating layers of thesame level in the adjacent memory blocks; and the conductor portions andthe conductor layers comprise the same materials, and the insulatingportions and the insulating layers comprise the same materials.
 17. Athree-dimensional (3D) memory device, comprising: a memory stack over asubstrate, the memory stack comprising interleaved a plurality ofconductor layers and a plurality of insulating layers; a plurality ofchannel structures extending vertically in the memory stack; a sourcestructure comprising a plurality of source portions and extending in thememory stack; and a support structure between adjacent ones of thesource portions and comprising a plurality of interleaved conductorportions and insulating portions, wherein a top one of the conductorportions is coplanar with a top one of the conductor layers, andadjacent ones of the source portions are conductively connected to oneanother.
 18. The 3D memory device of claim 17, wherein the sourcestructure further comprises a connection layer in contact with andconductively connected to the adjacent ones of the source portions, theconnection layer being a conductive layer.
 19. The 3D memory device ofclaim 18, wherein the connection layer comprises at least one oftungsten, cobalt, aluminum, copper, silicides, or polysilicon.
 20. The3D memory device of claim 18, wherein: the connection layer ispositioned over each of the adjacent ones of the source portions; andthe connection layer is over the support structure.